Computing devices today include servers, desktops, laptops and mobile devices such as phones and tablets. In typical usage only authorized users are allowed to use the device. However due to various security weaknesses, unauthorized human and machine intrusion may occur.
To prevent unauthorized users from using a computing device, conventional techniques authenticate the user through an entry one-time authentication mechanism. This includes single-factor authentication (such as login/password) to multi-factor authentication (using techniques such as biometrics, hardware tokens, etc.). Security holes exist with these methods. For instance, user passwords can be compromised by either technical or social engineering techniques. Malicious users may also find ways to bypass the authentication systems through application backdoors or holes.